In recent years, along with increasing generalization of a hybrid electric vehicle (HEV) and an electric vehicle (EV), it has been made possible for these vehicles to allow an external device to control the vehicle control apparatus via a communication network. In addition, as a related art, there is disclosed a technique that performs remote diagnosis or remote maintenance or the like of a vehicle system by accessing vehicle function apparatuses (such as an engine control apparatus, a fuel supply apparatus, or brake control apparatus) from an external device via a communication network.
However, if a third party not directly related to the operation of a vehicle controls a vehicle control apparatus from an external device, such control may interfere with safe driving. Accordingly, it is necessary to allow only a person related to the operation of the vehicle to access the vehicle control apparatus. Patent Literature (PTL) 1 discloses a technique that provides a firewall to the input side of a vehicle control apparatus, and allows the person in charge of the vehicle to access the interface of the vehicle system from an external device and to perform remote diagnosis or remote maintenance only when this firewall validates the external input.